Optical film, optical-film-equipped polarizing plate, and display device

Abstract

An optical film according to an embodiment includes a substrate 101, a surface member 102 provided on a front surface of the substrate 101, and an optical functional layer 103 provided on a back surface of the substrate 101. The optical functional layer 103 includes a low-refractive index layer 104 and a high-refractive index layer 105, and an interface between the low-refractive index layer 104 and the high-refractive index layer 105 has a recessed/protruding shape. The refractive index of the high-refractive index layer 105, the refractive index of the substrate 101, and the refractive index of the surface member 102 become smaller in this order.

The invention claimed is: 
     
         1 . An optical film comprising:
 a substrate;   a surface member provided on a front surface of the substrate; and   an optical functional layer provided on a back surface of the substrate,   wherein the optical functional layer includes a first layer and a second layer that has a refractive index different from a refractive index of the first layer and that is joined to the first layer on the substrate side of the first layer,   wherein a first interface between the first layer and the second layer has a recessed/protruding shape,   wherein the refractive index of the second layer, a refractive index of the substrate, and a refractive index of the surface member become smaller in this order, and   wherein a coloring material is provided closer to the second layer than to the first interface.   
     
     
         2 . The optical film according to  claim 1 , wherein the refractive index of the first layer is smaller than the refractive index of the second layer. 
     
     
         3 . The optical film according to  claim 1 , wherein each of recessed portions and protruding portions of the recessed/protruding shape includes a flat portion extending along a film surface of the optical film. 
     
     
         4 . The optical film according to  claim 1 ,
 wherein the optical functional layer further includes a third layer stacked to a side of the first layer opposite to the second layer,   wherein the refractive index of the first layer is different from a refractive index of the third layer, and   wherein a second interface between the first layer and the third layer has a recessed/protruding shape.   
     
     
         5 . The optical film according to  claim 4 , wherein the refractive index of the first layer is smaller than the refractive index of the third layer. 
     
     
         6 . The optical film according to  claim 4 , wherein the refractive index of the first layer is larger than the refractive index of the third layer. 
     
     
         7 . The optical film according to  claim 4 , wherein a pitch of recesses and protrusions of the recessed/protruding shape of the first interface is larger than a pitch of recesses and protrusions of the recessed/protruding shape of the second interface. 
     
     
         8 . The optical film according to  claim 1 , further comprising a colored layer stacked to a side of the second layer of the optical functional layer,
 wherein the coloring material is included in the colored layer.   
     
     
         9 . The optical film according to  claim 8 , wherein the coloring material is included in the colored layer by a proportion of 1.0 mass % or more and 5.0 mass % or less. 
     
     
         10 . The optical film according to  claim 1 , wherein the coloring material has a black color. 
     
     
         11 . The optical film according to  claim 1 , wherein, in the optical film, the first layer has adhesiveness. 
     
     
         12 . A display device comprising:
 the optical film according to  claim 1 ; and   a liquid crystal panel,   wherein the optical film is disposed so that the first layer faces a display surface side of the liquid crystal panel with respect to the second layer.   
     
     
         13 . A display device comprising:
 the optical film according to  claim 1 ; and   an organic LED panel,   wherein the optical film is disposed so that the first layer faces a display surface side of the organic LED panel with respect to the second layer.   
     
     
         14 . An optical-film-equipped polarizing plate comprising:
 the optical film according to  claim 1 ; and   a polarizing plate affixed to the optical film.   
     
     
         15 . The optical-film-equipped polarizing plate according to  claim 14 , wherein a layer of the optical film in contact with the polarizing plate also serves as an adhesive layer for the polarizing plate. 
     
     
         16 . The optical-film-equipped polarizing plate according to  claim 14 , further comprising an adhesive layer between the optical film and the polarizing plate. 
     
     
         17 . An optical-film-equipped polarizing plate comprising:
 the optical film according to  claim 1 ;   a polarizer affixed to the optical film; and   an adhesive layer affixing the optical film and the polarizer to each other,   wherein the polarizer is affixed to the optical film via only the adhesive layer.   
     
     
         18 . An optical-film-equipped polarizing plate comprising:
 the optical film according to  claim 1 ; and   a polarizer affixed to the optical film,   wherein a layer of the optical film in contact with the polarizer also serves as an adhesive layer for the polarizer, and   wherein the polarizer is directly affixed to the optical film.   
     
     
         19 . An optical film comprising:
 a substrate;   a surface member provided on a front surface of the substrate; and   an optical functional layer provided on a back surface of the substrate,   wherein the optical functional layer includes a first layer and a second layer that has a refractive index different from a refractive index of the first layer and that is joined to the first layer on the substrate side of the first layer,   wherein a first interface between the first layer and the second layer has a recessed/protruding shape,   wherein the refractive index of the second layer, a refractive index of the substrate, and a refractive index of the surface member become smaller in this order, and   wherein the refractive index of the first layer is larger than the refractive index of the second layer.   
     
     
         20 . An optical film comprising:
 a substrate;   a surface member provided on a front surface of the substrate; and   an optical functional layer provided on a back surface of the substrate,   wherein the optical functional layer includes a first layer and a second layer that has a refractive index different from a refractive index of the first layer and that is joined to the first layer on the substrate side of the first layer,   wherein a first interface between the first layer and the second layer has a recessed/protruding shape,   wherein the refractive index of the second layer, a refractive index of the substrate, and a refractive index of the surface member become smaller in this order,   wherein the optical functional layer further includes a third layer stacked to a side of the first layer opposite to the second layer,   wherein the refractive index of the first layer is different from a refractive index of the third layer, and   wherein a second interface between the first layer and the third layer has a recessed/protruding shape.